Classifications

• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D163/00—Coating compositions based on epoxy resins; Coating compositions based on derivatives of epoxy resins
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F8/00—Chemical modification by after-treatment
  • C08F8/42—Introducing metal atoms or metal-containing groups
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D133/00—Coating compositions based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides, or nitriles thereof; Coating compositions based on derivatives of such polymers
  • C09D133/04—Homopolymers or copolymers of esters
  • C09D133/06—Homopolymers or copolymers of esters of esters containing only carbon, hydrogen and oxygen, the oxygen atom being present only as part of the carboxyl radical
  • C09D133/062—Copolymers with monomers not covered by C09D133/06

Definitions

• the present invention relates to a novel aqueous curable resin composition which is suited for use as an aqueous coating composition. More particularly, the present invention relates to an aqueous curable resin composition the cured article of which is superior in the water resistance and weather resistance, and which is also suited for use as an aqueous normal temperature-curable coating composition, the aqueous curable resin composition comprising an aqueous dispersion, as a main agent, containing gel-like resin dispersed particles having a functional group selected from a salt of a tertiary amino group or a salt of an acid group dispersed in an aqueous medium, and a compound having both an epoxy group and a hydrolyzable silyl group, as a curing agent.
• this aqueous emulsion composition has the fatal problem for a coating composition that the cured article has poor water resistance because emulsifiers or surfactants must be used. Therefore, its uses are limited. That is, at present, the performance of the coating film is still inferior to that of an organic solvent based coating composition.
• Japanese Patent Application, First Publication No. Hei 8-104846 discloses an aqueous normal temperature-curable resin composition wherein the water resistance and especially the weather resistance of the coating film is improved by using an aqueous compound, which is obtained by dispersing or dissolving a vinyl polymer having a tertiary amino group and/or an acid group neutralized with an acidic compound, or a vinyl polymer having an acid group and/or a tertiary amino group neutralized with a basic compound, in combination with a compound having both an epoxy group and a hydrolyzable silyl group.
• an aqueous compound which is obtained by dispersing or dissolving a vinyl polymer having a tertiary amino group and/or an acid group neutralized with an acidic compound, or a vinyl polymer having an acid group and/or a tertiary amino group neutralized with a basic compound, in combination with a compound having both an epoxy group and a hydrolyzable silyl group.
• the aqueous normal temperature-curable resin composition described in Japanese Patent Application, First Publication No. Hei 8-104846, as before, cannot attain satisfactory water resistance and weather resistance of the cured coating film and the performance of the coating film is inferior to an organic solvent based coating composition.
• an object of the present invention to remarkably improve the water resistance and weather resistance of the cured coating film in the aqueous curable resin composition.
• an excellent cured coating film which is equivalent to that obtained with organic solvent based coating compositions can be obtained by using an aqueous dispersion as a main agent, which contains, as essential components, gel-like resin dispersed particles having a functional group selected from a salt of a tertiary amino group or a salt of an acid group and an aqueous medium, and using a compound having both an epoxy group and a hydrolyzable silyl group, as a curing agent.
• an aqueous dispersion which contains, as essential components, gel-like resin dispersed particles having a functional group selected from a salt of a tertiary amino group or a salt of an acid group and an aqueous medium, and using a compound having both an epoxy group and a hydrolyzable silyl group, as a curing agent.
• the present invention relates to a two-pack aqueous curable resin composition comprising a combination of
• the gel-like resin dispersed particles used in the present invention have a functional group selected from a salt of a tertiary amino group and a salt of an acid group, thereby exerting self-dispersion properties in the aqueous medium.
• a functional group selected from a salt of a tertiary amino group and a salt of an acid group, thereby exerting self-dispersion properties in the aqueous medium.
• the degree of gelation of the gel-like resin dispersed particles, which exist in the aqueous dispersion (I), is preferably within such a range that the aqueous dispersion (I) preferably has a light transmittance of 95% or less when it is made into a tetrahydrofuran solution having a solid content of 5% by weight (prepared by dissolving in tetrahydrofuran an aqueous dispersion having a solid content of 35% by weight).
• the light transmittance when the aqueous dispersion (I) is made into a tetrahydrofuran solution having a solid content of 5% by weight is the light transmittance obtained using a spectrophotometer to measure the light transmittance of a sample obtained by dissolving in tetrahydrofuran an aqueous dispersion (I) having a solid content of 35% by weight, to thereby reduce the solid content to 5% by weight.
• the light transmittance obtained by measuring the light transmittance (%) of the sample using a rectangular cell made of glass having an optical path length of 10 mm in the presence of a light source having a wavelength of 640 nm.
• the spectrophotometer include "Shimadzu Spectrophotometer UV-1200" manufactured by Shimadzu Corp.
• the aqueous dispersion (I) shows the light transmittance (%) of 95% or less.
• the light transmittance is preferably reduced to 80% or less
• Examples of the gel-like resin dispersed particles having a functional group selected from a salt of a tertiary amino group and a salt of an acid group include (1) crosslinked urethane urea resin particles formed from a self-dispersing resin, a polyisocyanate compound and a polyfunctional amine described in Japanese Patent Application, First Publication No.
• the gel-like resin dispersed particles (3) and (4) are particularly preferred because of the excellent weather resistance of the cured coating film.
• the gel-like resin dispersed particles (3) can be prepared by dispersing the vinyl polymer (A-1) having a functional group selected from a salt of a tertiary amino group and a salt of an acid group, and a hydrolyzable silyl group, in an aqueous medium and performing the crosslinking reaction in the resulting dispersed particles.
• the gel-like resin dispersed particles (4) can be prepared by dispersing a mixture of the vinyl polymer (A-2) and the compound (B) in an aqueous medium and performing the crosslinking reaction in the resulting dispersed particles, wherein the vinyl polymer (A-2) has a functional group selected from a salt of a tertiary amino group and a salt of an acid group, or a functional group and a hydroxyl group or an epoxy group, and the compound (B) has a molecular weight of 500 or less, and has both a functional group, which has reactivity with a group selected from a salt of a tertiary amino group, a salt of an acid group, hydroxyl group or epoxy group, which exist in the vinyl polymer (A-2), and a hydrolyzable silyl group (hereinafter abbreviated as "compound (B)").
• vinyl polymer (A-1) or vinyl polymer (A-2) various vinyl polymers can be used and examples thereof include polymers made from monomers such as acrylic monomers, aromatic vinyl monomers, vinyl ester monomers, and fluoroolefin monomers.
• an acrylic polymer and a fluoroolefin polymer are preferred because the resulting cured coating film has good water resistance and weather resistance.
• the method of introducing the functional group selected from a salt of a tertiary amino group and a salt of an acid group into the vinyl polymer (A-2) includes, for example, a method of copolymerizing a vinyl monomer having a tertiary amino group or an acid group and, if necessary, the other vinyl monomer capable of copolymerizing with the monomer, and neutralizing a portion or all of the tertiary amino group or acid group to form a salt.
• polymerization is preferably conducted by using a hydroxyl group-containing vinyl monomer or an epoxy group-containing vinyl monomer in combination.
• Examples of the tertiary amino group-containing vinyl monomer include various (meth)acrylic acid ester monomers such as 2-dimethylaminoethyl (meth)acrylate, 2-diethylaminoethyl (meth)acrylate, 3-dimethylaminopropyl (meth)acrylate, 3-diethylaminopropyl (meth)acrylate, N-[2-(meth)acryloyloxyethyl]piperidine, N-[2-(meth)acryloyloxyethyl]pyrrolidine and N-[2-(meth)acryloyloxyethyl]morpholine; aromatic monomers such as 4-(N,N-dimethylamino)styrene, 4-(N,N-diethylamino)styrene and 4-vinylpyridine; (meth)actylamide monomers such as N-[2-dimethylaminoethyrenethyrenethyrene, 2-die
• (meth)acrylic acid ester monomers are particularly preferred because of excellent copolymerizability with other monomers.
• Examples of the acid group-containing vinyl monomer include (meth)acrylic acid, crotonic acid, maleic acid and itaconic acid; half esters such as half esters of maleic acid and an alkyl alcohol having 1 to 10 carbon atoms, half esters of itaconic acid and an alkyl alcohol having 1 to 10 carbon atoms, and half esters of fumaric acid and an alkyl alcohol having 1 to 10 carbon atoms; citraconic acid, 4-vinylbenzoic acid, cinnamic acid, mono 2-(meth)acryloyloxyethyl succinate and 2-(meth)acryloyloxyethyl phthalate; various monovinyl esters of various polyhydric carboxylic acids such as maronic acid, succinic acid, adipic acid and sebacic acid; phosphoric acid group-containing vinyl monmers such as mono ⁇ 2-(meth)acryloyloxyethyl ⁇ acid phosphate
• monomers having a carboxyl group are preferably used because of excellent copolymerizability with other monomers, and (meth)acrylic acid is particularly preferred.
• the hydrolyzable silyl group refers to an atomic group having a silicon atom bonded with an alkoxy group, a substituted alkoxy group, a phenoxy group, a phenoxy group, a halogen atom, an isopropenyloxy group, an acyloxy group or an iminooxy group, and is easily hydrolyzed to form a silanol group.
• Specific examples thereof include alkoxysilyl group, phenoxysilyl group, halosilyl group, isopropenyloxysilyl group, acyloxysilyl group and iminooxysilyl group.
• hydrolyzable silyl group-containing vinyl monomer (a-3) examples include ⁇ -(meth)acryloyloxypropyltrimethoxysilane, ⁇ -(meth)acryloyloxypropylmethyldimethoxysilane, ⁇ -(meth)acryloyloxypropyltriethoxysilane, ⁇ -(meth)acryloyloxypropylmethyldiethoxysilane, ⁇ -(meth)acryloyloxypropyltriisopropenyloxysilane, ⁇ -(meth)acryloyloxypropyltriiminooxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyl(tris- ⁇ -methoxyethoxy)silane, vinyltriacetoxysilane and vinyltrichlorosilane.
• ⁇ -(meth)acryloyloxypropyltrimethoxysilane, ⁇ -(meth)acryloyloxypropylmethyldimethoxysilane, ⁇ -(meth)acryloyloxypropyltriethoxysilane, ⁇ -(meth)acryloyloxypropylmethyldiethoxysilane and ⁇ -(meth)acryloyloxypropyltriisopropenyloxysilane are particularly preferred because an internal crosslinking rate can be easily adjusted.
• (a-4) examples include (meth)acrylic acid esters such as methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, iso-propyl (meth)acrylate, n-butyl (meth)acrylate, iso-butyl (meth)acrylate, tert-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, cyclohexyl (meth)acrylate, benzyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate; unsaturated dibasic acid dialkyl esters such as dimethyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, iso
• VEOVA nitrile group-containing vinyl monomers such as acrylonitrile
• various (per)fluoroalkyl group-containing vinyl monomers such as fluoroalkyl (meth)acrylate, perfluoroalkyl (meth)acrylate, perfluorocyclohexyl (meth)acrylate, diperfluorocyclohexyl fumarate and N-isopropylperfluorooctanesulfonamideethyl (meth)acrylate
• monomers having a polyether segment such as polyethylene glycol (meth)acrylate, polypropylene glycol (meth)acrylate, polytetramethylene glycol (meth)acrylate, monoalkoxy ethylene glycol (meth)acrylate and monoalkoxy propylene glycol (meth)acrylate as far as the water resistance and weather resistance are not adversely affected.
• (meth)acrylic acid esters are particularly preferred because of excellent copolymerizability with other monomers.
• the vinyl polymer (A-1) and vinyl polymer (A-2) may be prepared from the monomers described above in detail according to a conventionally known polymerization method.
• a solution radical polymerization method is particularly preferred because it is the most simple.
• solvents to be used include various hydrocarbon solvents such as toluene, xylene, cyclohexane, n-hexane and octane; alcohol solvents such as methanol, ethanol, iso-propanol, n-butanol, iso-butanol, sec-butanol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monoisopropyl ether and ethylene glycol monobutyl ether; ester solvents such as methyl acetate, ethyl acetate, n-butyl acetate and amyl acetate; and ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone. These solvents may be used alone or in combination.
• the polymerization may be carried out by a conventional method.
• various chain transfer agents such as lauryl mercaptan, octyl mercaptan, dodecyl mercaptan, 2-mercaptoethanol, octyl thioglycolate, 3-mercaptopropionic acid and ⁇ -methylstyrene dimer can also be used as a molecular weight modifier.
• the amount of the salt of the tertiary amino group to be introduced into the vinyl polymer (A-1) or vinyl polymer (A-2) thus prepared is not specifically limited as far as the resin component in the aqueous medium can exhibit self-dispersion properties, and is specifically within a range from 0.03 to 2.5 mol based on 1,000 g of the solid content in view of dispersion in the aqueous medium.
• the amount is properly within a range from 0.05 to 1.5 mol, and most preferably from 0.05 to 0.5 mol.
• the amount of the salt of the tertiary amino group is preferably adjusted within a range from 0.03 to 2.5 mol, more preferably from 0.05 to 1.5 mol, and most preferably from 0.05 to 0.5 mol, based on 1,000 g of the solid content.
• the amount of the salt of the acid group to be introduced into the vinyl polymer (A-1) or vinyl polymer (A-2) is not specifically limited, similar to the case of the salt of the tertiary amino group, as far as the resin component in the aqueous medium can exhibit self-dispersion properties, and is preferably within a range from 0.1 to 1.0 mol, and most preferably from 0.3 to 0.7 mol, based on 1,000 g of the solid content of the vinyl polymer (A-1) or vinyl polymer (A-2).
• the amount of the salt of the acid group is preferably within a range from 0.1 to 1.0 mol, and most preferably from 0.3 to 0.7 mol, based on 1,000 g of the solid content.
• the amount of the hydrolyzable silyl group in the vinyl polymer (A-1) is not specifically limited and the proportion of the hydrolyzable silyl group-containing vinyl monomer (a-3) is preferably within a range from 0.3 to 15% by weight based on the total monomers constituting the vinyl polymer (A-1).
• the proportion is 0.3% by weight or more, the drying properties are further improved.
• the proportion is 15% by weight or less, the alkali resistance and water resistance of the cured coating film are more improved.
• the proportion is preferably within a range from 0.5 to 10% by weight.
• Examples of the hydroxyl group-containing vinyl monomer used to introduce a hydroxyl group and an epoxy group, which exist in the vinyl polymer (A-2), include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate, and examples of the epoxy group-containing vinyl monomer include glycidyl (meth)acrylate and ( ⁇ -methyl)glycidyl (meth)acrylate.
• the amount of the group contained in the vinyl polymer (A-2) which is involved in the reaction with the compound (B) is not specifically limited and the proportion of (a-1) or (a-2) involved in the reaction with the hydroxyl group-containing vinyl monomer, the epoxy group-containing vinyl monomer or the compound (B) is preferably within a range from 0.3 to 15% by weight based on the total monomers constituting the vinyl polymer (A-2).
• the proportion is 0.3% by weight or more, the drying properties are further improved.
• the proportion is 15% by weight or less, the alkali resistance and water resistance of the cured coating film are more improved.
• the proportion is preferably within a range from 0.5 to 10% by weight.
• Examples of the compound (B) include various epoxysilane compounds such as ⁇ -glycidoxypropyltrimethoxysilane, ⁇ -glycidoxypropyltriethoxysilane, ⁇ -glycidoxypropylmethyldimethoxysilane, ⁇ -glycidoxypropylmethyldiethoxysilane, ⁇ -(3,4-epoxycyclohexyl)ethyltrimethoxysilane, ⁇ -(3,4-epoxycyclohexyl)ethyltriethoxysilane, ⁇ -(3,4-epoxycyclohexyl)ethylmethyldiethoxysilane, ⁇ -glycidoxypropyltriisopropenyloxysilane and ⁇ -glycidoxypropyltriiminooxysilane; various adducts of isocyanatesilane compounds and glycidol, such as ⁇ -isocyanatepropyltriiso
• An appropriate compound (B) is selected according to the kind of crosslinkable functional group in the vinyl polymer (A-2).
• the crosslinkable functional group in (A-2) is, for example, a hydroxyl group
• an isocyanatesilane compound is appropriate.
• an epoxysilane compound is appropriate.
• an aminosilane compound is appropriate.
• the amount of the compound (B) with regard to the vinyl polymer (A-2) is preferably adjusted such that the equivalent ratio of tertiary amino groups, acid groups, hydroxyl groups or epoxy groups involved in the reaction with the compound (B) in the vinyl polymer (A-2) to functional groups having reactivity with groups selected from salts of tertiary amino groups, salt of acid groups, hydroxyls group and epoxy groups, which exist in the vinyl polymer (A-2), in the compound (B) is from 0.8 to 1.2.
• the compound (B) is mixed with the vinyl polymer (A-2), the compound (B) is preferably mixed with (A-2) as uniformly as possible under conditions in which no gelation occurs during mixing.
• the vinyl polymer (A-1) or vinyl polymer (A-2) can be made into an aqueous dispersion having self-dispersion properties by neutralizing a portion or all of the tertiary amino groups or acid groups; which exists in the polymer, after the polymerization of the monomer.
• the monomer component is mixed with the compound (B) and then a portion or all of the tertiary amino group or acid groups which exists in the mixture can be neutralized.
• the neutralization is conducted by adding either of an acidic compound or a basic compound.
• a neutralized substance having water dispersion properties can be obtained by partially or completely neutralizing the tertiary amino group with the acidic compound.
• the acid group is neutralized, a neutralized substance having water dispersion properties can be obtained by partially or completely neutralizing the acid group with the basic compound.
• the acidic compound is not specifically limited and examples thereof include carboxylic acids having 1 to 10 carbon atoms, such as formic acid, acetic acid, propionic acid, butyric acid, 2-methylbutyric acid, isovaleric acid, trimethylacetic acid, glycolic acid and lactic acid; various mono- or dialkyl esters of phosphoric acid, such as phosphoric acid monomethyl ester, phosphoric acid dimethyl ester, phosphoric acid mono-iso-propyl ester, phosphoric acid di-isopropyl ester, phosphoric acid mono-2-ethylhexyl ester and phosphoric acid di-2-ethylhexyl ester; organic sulfonic acids such as methanesulfonic acid, propanesulfonic acid, benzenesulfonic acid and dodecylbenzenesulfonic acid; and various inorganic acids such as hydrochloric acid, sulfuric acid, nitric acid and phosphoric acid.
• Typical examples of the basic compound include organic amine compounds such as methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, n-butylamine, tri-n-butylamine, 2-amino-2-methylpropanol, 2-amino-ethanol and 2-dimethylaminoethanol; inorganic basic substances such as ammonia, sodium hydroxide and potassium hydroxide; quaternary ammonium hydroxides such as tetramethylammonium hydroxide, tetrabutylammonium hydroxide and trimethylbenzylammonium hydroxide.
• organic amine compounds such as methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, n-butylamine, tri-n-butylamine, 2-amino-2-methylpropanol, 2-amino-ethanol and 2-dimethylaminoethanol
• inorganic basic substances such
• ammonia and various amines are used, particularly preferably, because these compounds are sufficiently volatilized during drying and the amount remained in the coating film after drying is small and, therefore, the resulting cured coating film has good water resistance.
• the amount of the acidic compound to be added when neutralizing a tertiary amino group is an amount sufficient to enable the vinyl polymer (A-1) or vinyl polymer (A-2) to exert self-water dispersion properties when the vinyl polymer (A-1) or vinyl polymer (A-2) has only a salt of a tertiary amino group or has both a salt of a tertiary amino group and a salt of an acid group among a salt of a tertiary group and a salt of an acid group.
• the equivalent ratio of the acidic compound to that of the tertiary amino groups immediately after the polymerization of the vinyl polymer is preferably within a range from 0.1 to 2, and particularly preferably from 0.5 to 1.5.
• the equivalent ratio of the acidic compound to that of the tertiary amino groups excluding those involved in the reaction with the compound (B) is preferably within a range from 0.1 to 2, and particularly preferably from 0.5 to 1.5.
• the amount of the basic compound to be added when neutralizing acid groups is an amount enough to enable the vinyl polymer (A-1) or vinyl polymer (A-2) to exert self-water dispersion properties when the vinyl polymer (A-1) or vinyl polymer (A-2) has only a salt of an acid group or has both a salt of a tertiary amino group and a salt of an acid group.
• the equivalent ratio the basic compound to that of the acid groups immediately after the polymerization of the vinyl polymer is preferably within a range from 0.1 to 2, and particularly preferably from 0.5 to 1.5.
• the equivalent ratio of the basic compound to that of the acid groups excluding those involved in the reaction with the compound (B) is preferably within a range from 0.1 to 2, and particularly preferably from 0.5 to 1.5.
• either of a salt of a tertiary amino group or a salt of an acid group exists in the vinyl polymer (A-1) or vinyl polymer (A-2).
• the reactivity with the compound (II) having both an epoxy group and a hydrolyzable silyl group which is described hereinafter, is remarkably enhanced and drying properties for normal temperature-curable aqueous coating compositions are remarkably enhanced.
• acrylic emulsion composition obtained by the emulsion polymerization using an emulsifier or a surfactant has a high molecular weight and good drying properties, it shows satisfactory fast drying properties.
• the resin constituting the dispersed particles has a comparatively low molecular weight and is inferior in curability.
• the vinyl polymer (A-1) or vinyl polymer (A-2) since the vinyl polymer (A-1) or vinyl polymer (A-2) has both a salt of a tertiary amino group and a salt of an acid group, not only the reactivity with the compound (II) as a curing agent is remarkably enhanced, but also the curability in a two-pack curing system is remarkably improved because the dispersed particles are in the form of gel.
• the vinyl polymer (A-1) or the mixture of the vinyl polymer (A-2) and the compound (B) thus obtained is dispersed in the aqueous medium and then internally crosslinked in the dispersed particles.
• the neutralized substance is dispersed in water by merely adding water to the neutralized substance, continuously or intermittently, or adding the neutralized substance to water, continuously or intermittently, thus making it possible to obtain an aqueous dispersion.
• the vinyl polymer (A-1) or vinyl polymer (A-2) and water may be mechanically dispersed in the state of being from any previous mixing or the state of being previously mixed, using a dispersion apparatus having a high shear force.
• the vinyl polymer (A-1) before neutralization or a mixture of the vinyl polymer (A-2) before neutralization and the compound (B) may be mechanically dispersed in the state being from any previous mixing or the state of being previously mixed, using a dispersion apparatus having a high shear force.
• the resulting aqueous dispersion is internally crosslinked in the dispersed particles.
• the crosslinking reaction partially occurs sometimes in the preparation of the vinyl polymer (A-1) or vinyl polymer (A-2), it does not adversely affect the following water dispersion process as far as the fluidity is not completely lost by so-called gelation.
• the crosslinking reaction in the dispersed particles can be carried out by the formation of a disiloxane bond due to the condensation reaction between hydrolyzable silyl groups which exist in the dispersed particles.
• the siloxane crosslinking can be carried out by the condensation reaction between hydrolyzable silyl groups contained in the vinyl polymer (A-1).
• a disiloxane bond can be formed by the condensation reaction between hydrolyzable silyl groups in the compound (B) and the internal crosslinking is formed by the reaction between the vinyl polymer (A-2) and the compound (B).
• the crosslinking reaction is preferably promoted when the vinyl polymer (A-1) is dispersed in the aqueous medium, or after the vinyl polymer (A-2) and the compound (B) are dispersed in the aqueous dispersion and then uniformly dispersed.
• the degree to which the crosslinking reaction proceeds can be adjusted by controlling the temperature conditions after the dispersion and the time for which the temperature is maintained.
• the crosslinking reaction is preferably carried out at a temperature within a range from 20 to 100°C and, furthermore, the reaction product may be maintained at the temperature with a range from 40 to 100°C until the light transmittance of the dispersed particles becomes 95% or less.
• the organic solvent used in the preparation of the vinyl polymer (A-1) or vinyl polymer (A-2) is preferably removed, partially or completely, by heating or under reduced pressure after the water dispersion. Such a removal process can be carried out after the completion of the crosslinking reaction, or simultaneously with the crosslinking reaction.
• the dispersion into the aqueous medium is carried out under the condition where the light transmittance becomes 95% or more when the dispersion is made into a tetrahydrofuran solution having a solid content of 5% by weight, and then the crosslinking reaction is carried out, thereby controlling the light transmittance to 95% or less.
• the two-pack aqueous curable resin composition of the present invention can be prepared by using the aqueous dispersion (I) thus obtained of the present invention in combination with the compound (II) having both an epoxy group and a hydrolyzable silyl group.
• a two-pack curable composition having not only water resistance and weather resistance of the coating film, but also excellent stain resistance, solvent resistance and chemical resistance can be obtained by using the aqueous dispersion of the present invention as a main agent and using a compound having both an epoxy group and a hydrolyzable silyl group as a curing agent.
• aqueous dispersion main agent
• curing agent aqueous dispersion
• curing agent a curing agent like the present invention
• An aqueous two-pack curing system has a problem that, since the resin as the main agent is not in the form of dispersed particles, the curing agent does not interfuse into the particles and, therefore, a cured coating film having a uniform crosslinking degree cannot be obtained and satisfactory physical properties for the coating film cannot be obtained.
• the crosslinking system of the present invention since the dispersed particles themselves are internally crosslinked even if the curing agent does not interfuse into water dispersed particles of the resin as the main agent, a cured coating film having an entirely uniform degree of crosslinking can be obtained, and thus the water resistance and weather resistance of the coating film are remarkably improved.
• the coating film is also superior in stain resistance, solvent resistance and chemical resistance.
• Examples of the compound (II) having both an epoxy group and a hydrolyzable silyl group include vinyl polymer having both an epoxy group and a hydrolyzable silyl group, and epoxy group-containing silane coupling agent.
• vinyl polymer having both an epoxy group and a hydrolyzable silyl group for example, the following vinyl polymers can be preferably used.
• Examples thereof include copolymer of hydrolyzable silyl group-containing vinyl monomer and epoxy group-containing vinyl monomer, and copolymer of hydrolyzable silyl group-containing vinyl monomer, epoxy group-containing vinyl monomer and other vinyl monomers.
• Examples of usable hydrolyzable silyl group-containing vinyl monomer include ⁇ -(meth)acryloyloxypropyltrimethoxysilane, ⁇ -(meth)acryloyloxypropylmethyldimethoxysilane, ⁇ -(meth)acryloyloxypropyltriisopropenyloxysilane, ⁇ -(meth)acryloyloxypropyltriiminooxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyl(tris- ⁇ -methoxyethoxy)silane, vinyltriacetoxysilane and vinyltrichlorosilane.
• epoxy group-containing vinyl monomer examples include glycidyl (meth)acrylate, ( ⁇ -methyl)glycidyl (meth)acrylate, 3,4-epoxycyclohexyl (meth)acrylate, allylglycidyl (meth)acrylate, 3,4-epoxyvinylcyclohexane, di( ⁇ -methyl)glycidyl maleate and di( ⁇ -methyl)glycidyl fumarate.
• Examples of the other copolymerizable vinyl monomer include vinyl monomer (a-4) described above.
• a conventionally known means can be used and examples thereof include a method of solution radical copolymerization of the monomers described above or a method of solution radical copolymerization of the monomer mixtures described above in the presence of various chain transfer agents having a hydrolyzable silyl group, for example, ⁇ -mercaptopropyltrimethoxysilane, ⁇ -mercaptopropyltriethoxysilane, ⁇ -mercaptopropylmethyldimethoxysilane, ⁇ -mercaptopropyltriisopropenyloxysilane and ⁇ -mercaptopropyltriiminooxysilane.
• chain transfer agents having a hydrolyzable silyl group for example, ⁇ -mercaptopropyltrimethoxysilane, ⁇ -mercaptopropyltriethoxysilane, ⁇ -mercaptopropylmethyldimethoxysilane, ⁇ -mercaptopropyltriisopropenyloxysi
• the vinyl polymer having both an epoxy group and a hydrolyzable silyl group is preferably mixed with the aqueous resin dispersion (I) as the main agent after dissolving in a proper organic solvent, when using as the curing agent.
• epoxy group-containing silane coupling agent examples include ⁇ -glycidoxypropyltrimethoxysilane, ⁇ -glycidoxypropyltriethoxysilane, ⁇ -glycidoxypropylmethyldimethoxysilane, ⁇ -glycidoxypropylmethyldiethoxysilane, ⁇ -(3,4-epoxycyclohexyl)ethyltrimethoxysilane, ⁇ -(3,4-epoxycyclohexyl) ethyltriethoxysilane, ⁇ -(3,4-epoxycyclohexyl)ethylmethyldiethoxysilane, ⁇ -glycidoxypropyltriisopropenyloxysilane or ⁇ -glycidoxypropyltriiminooxysilane; adduct of an isocyanatesilane compound such as ⁇ -isocyanatepropyltriisopropenyloxysilane or ⁇ -g
• an epoxy group-containing silane coupling agent is particularly preferred because the uniformity of the crosslinking degree of the coating film is improved.
• a mixing ratio of the aqueous dispersion (I) to the compound (II) is controlled such that a molar ratio represented by the number of moles of the epoxy group contained in the compound (II) to the total number of moles of the residual tertiary amino group and the residual acid group in the aqueous dispersion (I) (hereinafter referred to as "the ratio of the number of moles of the epoxy group in the compound (II) to the total number of moles of the residual tertiary amino group and the residual acid group in the aqueous dispersion (I)”) is within a range from 0.1 to 3.0, preferably from 0.3 to 2.0, and particularly preferably from 0.5 to 1.5.
• aqueous curable resin composition of the present invention by using a compound which has a hydrolyzable silyl group or a silanol group and does not have an epoxy group (hereinafter abbreviated as "compound (III)") in combination with the aqueous dispersion (I) and the compound (II), the weather resistance of the cured coating film can be further improved and the hardness can be further enhanced.
• compound (III) a compound which has a hydrolyzable silyl group or a silanol group and does not have an epoxy group
• the compound (III), which has a hydrolyzable silyl group or a silanol group and does not have an epoxy group include silicate compounds such as methyl silicate, ethyl silicate, isopropyl silicate and n-butyl silicate; trifunctional silane compounds such as methyltrimethoxysilane, phenyltrimethoxysilane, methyltriethoxysilane, phenyltriethoxysilane and isobutyltrimethoxysilane; difunctional silane compounds such as dimethyldimethoxysilane, dimethyldiethoxysilane, diethyldimethoxysilane, diethyldiethoxysilane and diphenyldimethoxysilane; halosilanes such as methyltrichlorosilane, phenyltrichlorosilane, ethyltrichlorosilane, dimethyldichlorosilane and diphenyldich
• the amount of the compound (III) is preferably within a range from 0.5 to 200 parts by weight, and particularly preferably from 1 to 100 parts by weight, based on 100 parts by weight of the resin solid content of the aqueous dispersion (I) in view of the effect of improving the weather resistance and hardness of the cured coating film.
• a curing catalyst (IV) can be added to the aqueous curable resin composition of the present invention.
• the curability can be further improved by adding the curing catalyst (IV).
• the curing catalyst (IV) include basic compounds such as lithium hydroxide, sodium hydroxide, potassium hydroxide and sodium methylate; metal containing compounds such as tetraisopropyl titanate, tetra-n-butyl titanate, tin octylate, lead octylate, cobalt octylate, zinc octylate, calcium octylate, zinc naphthenate, cobalt naphthenate, di-n-butyltin diacetate, di-n-octyltin dioctoate, di-n-butyltin dilaurate and di-n-butyltin maleate; dispersions of various metal containing compounds in water, obtained by using an emulsifier or a surfactant; and acid compounds such as p-toluenesulfonic acid, trichloroacetic acid, phosphoric acid, monoalkylphosphoric acid, dialkyl
• film forming auxiliaries such as isopropyl alcohol, sec-butanol, n-butanol, 2-ethylhexanol, 2-propoxyethanol, 2-n-butoxyethanol, 2-n-propoxypropanol, 3-n-propoxypropanol, 2-n-butoxypropanol, 3-n-butoxypropanol, 2-n-butoxyethyl acetate, diethylene glycol monobutyl ether, N-methylpyrrolidone, 2,2,4-trimethyl-1,3-pentanediol monobutyrate, dibutyl phthalate, and butylbenzyl phthalate, defoamers, organic pigments, inorganic pigments, plasticizers, antioxidants, ultraviolet absorbers, photostabilizers, leveling agents, repelling inhibitors, skinning inhibitors, dispersants and thickeners to the aqueous curable resin composition of the present invention, if necessary.
• film forming auxiliaries such as isoprop
• the aqueous medium (I) is mixed with the compound (II) having both an epoxy group and a hydrolyzable silyl group. It is preferred that the resulting aqueous curable resin composition is applied within one day (24 hours), and preferably 12 hours, after the completion of mixing.
• the two-pack aqueous curable resin composition of the present invention can be applied on various substrates by a conventional method and can be widely used because of its fast curability as compared with a conventional dispersion type coating composition.
• a cured coating film can be formed by drying at normal temperature for about 1 to 10 days, forcibly drying at a temperature ranging from 40 to 100°C for about 1 to 60 minutes, or baking and drying at a temperature ranging from 100 to 180°C for about 1 to 60 minutes.
• the organic solvent is less likely to be charged into the atmosphere and a cured article having excellent weather resistance, solvent resistance and chemical resistance can be obtained.
• it is made possible to achieve important properties during the coating operation such as fast drying properties and fast curability, and the resulting product is widely usable.
• the curable resin composition for aqueous coating composition of the present invention can be widely used as coating compositions for construction, roofing tiles, magnetic tiles, glass, woodwork and various plastic products, and coating compositions for various metal materials such as aluminum, stainless steel, chrome plating, galvanized iron sheet and tinned-sheet iron.
• an aqueous normal temperature-curable resin composition having remarkably improved drying properties and curability, an aqueous dispersion which serves as a main agent of the composition, and a method of preparing the aqueous dispersion can be provided without impairing the performance of the coating film, such as its water resistance and weather resistance.
• the aqueous curable resin composition of the present invention When using the aqueous curable resin composition of the present invention as the aqueous coating composition, it is possible to obtain a coating film which is less likely to discharge organic solvent into the atmosphere and which also has excellent solvent resistance and chemical resistance, in addition to obtaining properties in the coating film such as fast curability as well as water resistance and weather resistance.
• Example 1 Example 2
• Example 3 Comp.
• Example 2 Aqueous dispersion III-1 100 Aqueous dispersion III-2 100 Aqueous dispersion III-3 100 Aqueous dispersion 1 100 Aqueous dispersion 2 100 (R-930) 17.1 18.7 19.4 19.6 19.8 ⁇ -GPTMS 4.5 3.5 4.6 3.6 ⁇ -GPTES 4.7 Name of coating composition i-1 i-2 i-3 ii-1 ii-2 Examples Example 4 Example 5 Example 6 Example 7 Example 8 Aqueous dispersion III-1 100 Aqueous dispersion III-2 100 Aqueous dispersion III-3 100 100 (R-930) 19.3 18.7 18.7 18.7 18.7 ⁇ -GPTMS 4.6 3.4 4.5 4.5 4.5 DBTDL 0.03 (TSL) 20.0 (SH-6018) 2.0 Name of coating composition i-4 i-5 i-6 i-7 i-8 «Notes for Table 2-1 and Table 2-2» "R-930”: abbreviation of "TIPAQUE r-930" (trade name of titanium oxide manufactured by ISHIHARA
• Example 1 Comp.
• Example 2 Name of coating composition i-1 i-2 i-3 ii-1 ii-2 Gel fraction (%) 93 92 92 82 81 Drying properties (touch with finger) 25 25 27 55 58
• 72 70 Stain resistance ⁇ L -2.8 -2.4 -2.6 -8.2 -9.0
• Example 4 Example 5
• Example 6 Example 7
• Example 8 Name of coating composition i-4 i-5 i-6 i-7 i-8 Gel fraction (%) 93 92 94 97 97 Drying properties (touch with finger) 25 30 25 25 25 25 25 25
• Solvent resistance A film was rubbed 100 times (back and forth) with a felt impregnated with methyl ethyl ketone under a load of 500 g. Then, the appearance of the coating film was visually evaluated according to the following criteria. Criteria for evaluation are as follows. ⁇ : no change ⁇ : slight scratching ⁇ : severe loss of gloss Alkali resistance: An aqueous 5% sodium hydroxide solution was dropped on the film and, after the passage of 24 hours, the sodium hydroxide was washed off. Then, the appearance of the coating film was visually evaluated according to the following criteria. Criteria for evaluation are as follows.

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